2
Fit a stand mixer with the paddle attachment. Beat the bananas, peanut butter, sour cream, eggs, oil, brown sugar and vanilla until well blended, about 2 minutes. Spoon the flour mixture into the banana mixture and beat on low speed until just blended. Toss the peanut butter cups in the remaining ¼ cup flour (to help prevent sinking) and stir into the batter along with the chopped dark chocolate.